[zeromq-dev] Is Pub/Sub unreliable

Martin Sustrik sustrik at 250bpm.com
Wed Mar 10 08:45:24 CET 2010

Emit Sorrels wrote:

>> This works erratically. Sometimes receiver receives less than 20
>> messages; sometimes it receives NONE.
>> Is it the case that PUB/SUB sockets are unreliable? This is sort of a
>> surprise to me... If they are not, what could explain this behavior?
>> Thanks in advance.
> if a tree falls in the forest and no one is there to hear it does
> it make a sound? :P
> afaik, pub doesn't queue up all the messages you send and resend
> old messages to subs that connect later on. it isn't used for
> such a use case.

Right. PUB/SUB works like a radio transmission. PUB is emitting 
continuous stream of messages. Individual SUBs connect, start receiving 
the stream from the point where they joined in and eventually leave the 
stream later on.


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